An additional silver impregnation method for demonstration of degenerating nerve cells and processes in the central nervous system.

A new silver impregnation technique for frozen and paraffin sections of formalin-fixed nervous tissue has been devised by modifying the Fink-Heimer14 and De Olmos-Ingram6 methods. The modified versions have been combined into a single staining procedure. Cobalt or lead nitrate are substituted for uranyl nitrate. Silver nitrate in the impregnating solution is replaced by silver lactate or protargol. This procedure results in a preferential impregnation of degenerating perikarya, dendrites, axons and synaptic endings. It affords a more complete impregnation of 'preterminal' axonal arborizations than previous methods. The method is effective for the demonstration of degenerating terminals in the rat cerebellar cortex. Emphasis has been laid on the usefulness of the method for the study of drug-induced CNS lesions.